/*
 * arch/m68k/q40/q40ints.c
 *
 * Copyright (C) 1999,2001 Richard Zidlicky
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file COPYING in the main directory of this archive
 * for more details.
 *
 * .. used to be loosely based on bvme6000ints.c
 *
 */

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/irq.h>

#include <asm/machdep.h>
#include <asm/ptrace.h>
#include <asm/traps.h>

#include <asm/q40_master.h>
#include <asm/q40ints.h>

#include "q40.h"

/*
 * Q40 IRQs are defined as follows:
 *            3,4,5,6,7,10,11,14,15 : ISA dev IRQs
 *            16-31: reserved
 *            32   : keyboard int
 *            33   : frame int (50/200 Hz periodic timer)
 *            34   : sample int (10/20 KHz periodic timer)
 *
 */

static void q40_irq_handler(unsigned int, struct pt_regs *fp);
static void q40_irq_enable(struct irq_data *data);
static void q40_irq_disable(struct irq_data *data);

unsigned short q40_ablecount[35];
unsigned short q40_state[35];

static unsigned int q40_irq_startup(struct irq_data *data)
{
        unsigned int irq = data->irq;

        /* test for ISA ints not implemented by HW */
        switch (irq) {
        case 1: case 2: case 8: case 9:
        case 11: case 12: case 13:
                pr_warn("%s: ISA IRQ %d not implemented by HW\n", __func__,
                        irq);
                /* FIXME return -ENXIO; */
        }
        return 0;
}

static void q40_irq_shutdown(struct irq_data *data)
{
}

static struct irq_chip q40_irq_chip = {
        .name           = "q40",
        .irq_startup    = q40_irq_startup,
        .irq_shutdown   = q40_irq_shutdown,
        .irq_enable     = q40_irq_enable,
        .irq_disable    = q40_irq_disable,
};

/*
 * void q40_init_IRQ (void)
 *
 * Parameters:  None
 *
 * Returns:     Nothing
 *
 * This function is called during kernel startup to initialize
 * the q40 IRQ handling routines.
 */

static int disabled;

void __init q40_init_IRQ(void)
{
        m68k_setup_irq_controller(&q40_irq_chip, handle_simple_irq, 1,
                                  Q40_IRQ_MAX);

        /* setup handler for ISA ints */
        m68k_setup_auto_interrupt(q40_irq_handler);

        m68k_irq_startup_irq(IRQ_AUTO_2);
        m68k_irq_startup_irq(IRQ_AUTO_4);

        /* now enable some ints.. */
        master_outb(1, EXT_ENABLE_REG);  /* ISA IRQ 5-15 */

        /* make sure keyboard IRQ is disabled */
        master_outb(0, KEY_IRQ_ENABLE_REG);
}


/*
 * this stuff doesn't really belong here..
 */

int ql_ticks;              /* 200Hz ticks since last jiffy */
static int sound_ticks;

#define SVOL 45

void q40_mksound(unsigned int hz, unsigned int ticks)
{
        /* for now ignore hz, except that hz==0 switches off sound */
        /* simply alternate the ampl (128-SVOL)-(128+SVOL)-..-.. at 200Hz */
        if (hz == 0) {
                if (sound_ticks)
                        sound_ticks = 1;

                *DAC_LEFT = 128;
                *DAC_RIGHT = 128;

                return;
        }
        /* sound itself is done in q40_timer_int */
        if (sound_ticks == 0)
                sound_ticks = 1000; /* pretty long beep */
        sound_ticks = ticks << 1;
}

static irqreturn_t q40_timer_int(int irq, void *dev_id)
{
        ql_ticks = ql_ticks ? 0 : 1;
        if (sound_ticks) {
                unsigned char sval=(sound_ticks & 1) ? 128-SVOL : 128+SVOL;
                sound_ticks--;
                *DAC_LEFT=sval;
                *DAC_RIGHT=sval;
        }

        if (!ql_ticks) {
                unsigned long flags;

                local_irq_save(flags);
                legacy_timer_tick(1);
                timer_heartbeat();
                local_irq_restore(flags);
        }
        return IRQ_HANDLED;
}

void q40_sched_init (void)
{
        int timer_irq;

        timer_irq = Q40_IRQ_FRAME;

        if (request_irq(timer_irq, q40_timer_int, 0, "timer", NULL))
                panic("Couldn't register timer int");

        master_outb(-1, FRAME_CLEAR_REG);
        master_outb( 1, FRAME_RATE_REG);
}


/*
 * tables to translate bits into IRQ numbers
 * it is a good idea to order the entries by priority
 *
*/

struct IRQ_TABLE{ unsigned mask; int irq ;};
#if 0
static struct IRQ_TABLE iirqs[]={
  {Q40_IRQ_FRAME_MASK,Q40_IRQ_FRAME},
  {Q40_IRQ_KEYB_MASK,Q40_IRQ_KEYBOARD},
  {0,0}};
#endif
static struct IRQ_TABLE eirqs[] = {
  { .mask = Q40_IRQ3_MASK,      .irq = 3 },     /* ser 1 */
  { .mask = Q40_IRQ4_MASK,      .irq = 4 },     /* ser 2 */
  { .mask = Q40_IRQ14_MASK,     .irq = 14 },    /* IDE 1 */
  { .mask = Q40_IRQ15_MASK,     .irq = 15 },    /* IDE 2 */
  { .mask = Q40_IRQ6_MASK,      .irq = 6 },     /* floppy, handled elsewhere */
  { .mask = Q40_IRQ7_MASK,      .irq = 7 },     /* par */
  { .mask = Q40_IRQ5_MASK,      .irq = 5 },
  { .mask = Q40_IRQ10_MASK,     .irq = 10 },
  {0,0}
};

/* complain only this many times about spurious ints : */
static int ccleirq=60;    /* ISA dev IRQs*/
/*static int cclirq=60;*/     /* internal */

/* FIXME: add shared ints,mask,unmask,probing.... */

#define IRQ_INPROGRESS 1
/*static unsigned short saved_mask;*/
//static int do_tint=0;

#define DEBUG_Q40INT
/*#define IP_USE_DISABLE *//* would be nice, but crashes ???? */

static int mext_disabled;       /* ext irq disabled by master chip? */
static int aliased_irq;         /* how many times inside handler ?*/


/* got interrupt, dispatch to ISA or keyboard/timer IRQs */
static void q40_irq_handler(unsigned int irq, struct pt_regs *fp)
{
        unsigned mir, mer;
        int i;

//repeat:
        mir = master_inb(IIRQ_REG);
#ifdef CONFIG_BLK_DEV_FD
        if ((mir & Q40_IRQ_EXT_MASK) &&
            (master_inb(EIRQ_REG) & Q40_IRQ6_MASK)) {
                floppy_hardint();
                return;
        }
#endif
        switch (irq) {
        case 4:
        case 6:
                do_IRQ(Q40_IRQ_SAMPLE, fp);
                return;
        }
        if (mir & Q40_IRQ_FRAME_MASK) {
                do_IRQ(Q40_IRQ_FRAME, fp);
                master_outb(-1, FRAME_CLEAR_REG);
        }
        if ((mir & Q40_IRQ_SER_MASK) || (mir & Q40_IRQ_EXT_MASK)) {
                mer = master_inb(EIRQ_REG);
                for (i = 0; eirqs[i].mask; i++) {
                        if (mer & eirqs[i].mask) {
                                irq = eirqs[i].irq;
/*
 * There is a little mess wrt which IRQ really caused this irq request. The
 * main problem is that IIRQ_REG and EIRQ_REG reflect the state when they
 * are read - which is long after the request came in. In theory IRQs should
 * not just go away but they occasionally do
 */
                                if (irq > 4 && irq <= 15 && mext_disabled) {
                                        /*aliased_irq++;*/
                                        goto iirq;
                                }
                                if (q40_state[irq] & IRQ_INPROGRESS) {
                                        /* some handlers do local_irq_enable() for irq latency reasons, */
                                        /* however reentering an active irq handler is not permitted */
#ifdef IP_USE_DISABLE
                                        /* in theory this is the better way to do it because it still */
                                        /* lets through eg the serial irqs, unfortunately it crashes */
                                        disable_irq(irq);
                                        disabled = 1;
#else
                                        /*pr_warn("IRQ_INPROGRESS detected for irq %d, disabling - %s disabled\n",
                                                irq, disabled ? "already" : "not yet"); */
                                        fp->sr = (((fp->sr) & (~0x700))+0x200);
                                        disabled = 1;
#endif
                                        goto iirq;
                                }
                                q40_state[irq] |= IRQ_INPROGRESS;
                                do_IRQ(irq, fp);
                                q40_state[irq] &= ~IRQ_INPROGRESS;

                                /* naively enable everything, if that fails than    */
                                /* this function will be reentered immediately thus */
                                /* getting another chance to disable the IRQ        */

                                if (disabled) {
#ifdef IP_USE_DISABLE
                                        if (irq > 4) {
                                                disabled = 0;
                                                enable_irq(irq);
                                        }
#else
                                        disabled = 0;
                                        /*pr_info("reenabling irq %d\n", irq); */
#endif
                                }
// used to do 'goto repeat;' here, this delayed bh processing too long
                                return;
                        }
                }
                if (mer && ccleirq > 0 && !aliased_irq) {
                        pr_warn("ISA interrupt from unknown source? EIRQ_REG = %x\n",
                                mer);
                        ccleirq--;
                }
        }
 iirq:
        mir = master_inb(IIRQ_REG);
        /* should test whether keyboard irq is really enabled, doing it in defhand */
        if (mir & Q40_IRQ_KEYB_MASK)
                do_IRQ(Q40_IRQ_KEYBOARD, fp);

        return;
}

void q40_irq_enable(struct irq_data *data)
{
        unsigned int irq = data->irq;

        if (irq >= 5 && irq <= 15) {
                mext_disabled--;
                if (mext_disabled > 0)
                        pr_warn("q40_irq_enable : nested disable/enable\n");
                if (mext_disabled == 0)
                        master_outb(1, EXT_ENABLE_REG);
        }
}


void q40_irq_disable(struct irq_data *data)
{
        unsigned int irq = data->irq;

        /* disable ISA iqs : only do something if the driver has been
         * verified to be Q40 "compatible" - right now IDE, NE2K
         * Any driver should not attempt to sleep across disable_irq !!
         */

        if (irq >= 5 && irq <= 15) {
                master_outb(0, EXT_ENABLE_REG);
                mext_disabled++;
                if (mext_disabled > 1)
                        pr_info("disable_irq nesting count %d\n",
                                mext_disabled);
        }
}